With the development of science and technology, flat panel display devices (e.g., liquid crystal display devices) have many advantages of high display quality, small volume, light weight and wide application range and thus are widely used in consumer electronics products such as mobile phones, laptop computers, desktop computers and televisions, etc. Moreover, the liquid crystal display devices have evolved into a mainstream display in place of cathode ray tube (CRT) displays.
In order to achieve the purposes of image contrast improvement, color optimization and low power consumption, backlight sources of liquid crystal display devices have been gradually changed from cold cathode fluorescent lamps to light emitting diodes. FIG. 1 illustrates a schematic system architecture of a conventional liquid crystal display device 10 using a LED backlight source. In particular, the liquid crystal display device 10 includes a timing controller 11, a DC/DC (i.e., direct current to direct current) converter 12, a negative charge pump circuit 13, a LED driver 14, a gate driving circuit 15, a source driving circuit 16, a liquid crystal display panel 17 and a LED backlight source 18. The DC/DC converter 12, the negative charge pump circuit 13 and the LED driver 14 as a whole are termed as power management and control module 19. Generally, the DC/DC converter 12 has a group of boost-type DC/DC topology circuit included therein, and the LED driver 14 has another group of boost-type DC/DC topology circuit included therein. A primary principle of the liquid crystal display device 10 will be described as follows. More specifically, the timing controller 11 receives image data LVDS_DATA from a system end 20 to generate display driving signals to the gate driving circuit 15 and the source driving circuit 16 and thereby for image display on the liquid crystal display panel 17. The DC/DC converter 12 receives an input voltage VIN and a pulse width modulation signal PWM_EN from the system end 20 to generate voltage signals AVDD, V_LOGIC and VGH respectively for a power supply terminal of the source driving circuit 16, a power supply terminal of the timing controller 11 and a logic high power supply terminal of the gate driving circuit 15. The negative charge pump circuit 13 externally connected to the DC/DC converter 12 generates a voltage signal VGL for a logic low power supply terminal of the gate driving circuit 15. The LED driver 14 receives another input voltage VLED_EN from the system end 20 and thereby performs a DC boost operation to generate an analog high voltage signal VLED_OUT for driving the LED backlight source 18. An enable signal VLED_EN inputted to the LED driver 14 from the system end 20 is for controlling whether to turn on the LED backlight source 18.
However, the circuit for generating the voltage signal VGH and the driver for the LED backlight source 18 respectively are individual circuit blocks, so that the usage area of printed circuit board assembly (PCBA), the amount of circuit traces and the power consumption of whole system are large consequently.